Non-specific body defencesThe inflammatory response
The immune system defends humans from pathogens. Physical and chemical barriers prevent infection. White blood cells attack pathogens. Immunisations usually involve injecting inactive pathogens.
The inflammatory response is a localised defence mechanism used by the body following a physical injury or infection.
In response to injury and infection, specialised immune cells called mast cells release histamine.
Histamine causes blood vessels to widen (vasodilationThe increase in diameter of the skin arterioles to increase blood flow and increase heat loss by radiation.). This increases blood flow to the area. The increased blood flow leads to an accumulation of phagocytesCells, such as white blood cells, that engulf and absorb waste material, harmful microorganisms, or other foreign bodies in the bloodstream and tissues. and clotting elements at the site of infection.
It follows five stages:
physical injury or infection
mast cells release chemical called histamine
histamine stimulates blood vessels to vasodilate and increases permeability of capillaries
this causes an increased blood flow
phagocytes and clotting elements accumulate at the site of injury or infection
